In the meat packing industry, techniques are known for the automatic and semiautomatic filling of various types of casings with viscous meat emulsion. In general, these techniques include positioning a shirred continuous film casing length over a stuffing horn and thereafter continuously deshirring the casing and stuffing the deshirred casing with viscous meat emulsion fed under pressure through the stuffing horn and into the casing interior. As used herein, the term casing or tubular casing is intended to mean tubing of natural or manufactured materials, and the term "casing length" is intended to mean continuous tubular casing lengths. Shirred tubular casings are also known to persons familiar with the art as "sticks", such "sticks" being long lengths of casing having a substantially large bore, which have been shirred and compressed into short compact self-sustaining lengths, or which may be a package of shirred and compressed casing sheathed inside a retaining sleeve. Apparatus and processes are well known in the food casing art for producing shirred tubular cellulosic food casings such as, for example, the apparatus and processes disclosed in U.S. Pat. Nos. 2,983,949 and 2,984,574 to Matecki. These apparatus may be employed in the preparation of pleated and compressed tubular casings wherein the compression ratios (unshirred to shirred stick length) are in the order of at least about 40:1 and up to about 100:1 or even greater. Using suitable food stuffing machinery, casing lengths can be stuffed and formed into unit size links of particulate or comminuted viscous materials, such as meat emulsions or the like.
In the art of producing sausages and similar food products, the finely divided meat compositions commonly referred to as emulsions, are conventionally stuffed into the tubular casing materials of long length which, as stated above, may be of natural or manufactured materials. Large sausage products used in slicing for multislice package putup are usually made in casings which range in size from the trade designation No. 6 (101 mm. diameter) to No. 9 (129 mm. diameter). In the production of large sausage products, a clip closed end casing of precut length is first manually sheathed over the end of a stuffing horn and then stuffed with a food emulsion. The stuffed casing is then tied, twisted or clipped into predetermined unit length cylindrical packages.
The thusly stuffed and encased food emulsion is subsequently cooked and cured according to conventional processes. A large percentage of these large sausage products are thereafter sliced and packaged into units of predetermined weight and slice count for retail sale. The high speed slicing devices employed in such packaging operations are pre-set to yield a specific weight-by-slice count for use in obtaining unit packages of equal weight. Therefore an important aspect of a commercially acceptable large sausage product is that the tubular finished processed sausage product have a substantially uniform diameter from end to end and in successive pieces of the same designated size. Moreover, the diameter of the slices must be uniformly precise in order to assure that the slices will fit into the preformed rigid packaging frequently used.
Since a large sausage casing stuffed with a food emulsion has two generally hemispherical, rounded ends, these rounded ends are generally not used in producing equal weight packages and are either discarded or reworked. Thus another aspect of importance commercially, is to have a large sausage casing stuffed with uniform tight ends, to thereby mimimize the amount of food product cut off from the cylindrical portion.
Years of commercial utilization of manufactured sausage casings such as prepared from unsupported or fibrous reinforced cellulose have provided the experience for determining optimum stuffing and processing conditions for various classes of sausage product. Sausage generally needs to be encased or stuffed to "green" or unprocessed diameters that have been selected and recommended for such optimum performance. The recommended stuffing diameter for each size and type of casing has been established and tabulated in recommended operating procedures determined by the casing manufacturer for guidance of the sausage maker.
When a casing is understuffed from the recommended "green" diameter, the result generally is a processed product that is not uniform in diameter from end to end and from piece to piece; the product is undesirably wrinkled in appearance; and the processed sausage may have an emulsion breakdown yielding undesirable pockets of fat or liquid.
When a casing is overstuffed from the recommended "green" diameter, the casing may split or break apart at the stuffing station or subsequently, in transport to or in the cooking/smoking processing operations. This results in a costly waste of meat and in the labor expense for cleanup.
For many years, the apparatus and methods employed to prepare the encased food products and particularly food products encased in large diameter casing have relied upon manual manipulation in controlling the stuffing of food emulsion into predetermined length sausage links or packages. Recently, advances in the art have resulted in the introduction of apparatus for machine control of the stuffing operation which have provided means for preparing uniformly sized encased products such as disclosed, for example, in U.S. Pat. Nos. 2,871,508, 2,999,270, 3,264,679 3,317,950, 3,454,980, 3,457,588, 3,553,769, 3,621,513, 3,659,317 and 3,751,764.
Although many of the prior art stuffing devices generally provide a fairly wide range of adjustment for producing stuffed casings of desired diameter, the adjustments are usually left to the judgment of the operator, thereby resulting in understuffing or overstuffing caused by deviation from the optimum size recommended by the casing manufacturer. In addition, the prior art devices do not have means for controlling the shape and tightness of stuffing for both the leading and trailing ends of the stuffed casing. However, in U.S. application Ser. No. 627,252 filed Oct. 30, 1975 in the name of V. Kupcikevicius et al., filed concurrently with this application, an apparatus is disclosed for stuffing flowable product into a shirred tubular casing article containing a diameter sizing means confined within a deshirred portion of one closed end and containing means to automatically stretch and snub a casing to a predetermined diameter as it is being suffed and having control means regulating the shape for the fore end and the aft end portions of a clip closed stuffed product. The specific details of this automatic stuffing apparatus are disclosed in said application and are incorporated herein by reference.
U.S. Pat. No. 3,975,795 filed in the name of V. Kupcikevicius et al. On Jan. 20, 1975 discloses an apparatus for stuffing cold, viscous product into normally flexible film tubing to produce stuffed tubular products on a continuous basis having a preselected length and diameter. The details of the the construction of this apparatus are disclosed in said application and are incorporated herein by reference.
One disadvantage of the prior art devices for stuffing tubular articles on a continuous basis is that an operator has to remain at the stuffing site to be ready to terminate the stuffing operation just prior to runout of the shirred casing. If the product flow control is not terminated, viscous material will be dispersed from the outlet end of the feed horn all over the apparatus, thereby not only causing waste of the material but also the expenditure of time for a cleanup operation before the stuffing cycle can be repeated. In addition, even when the operator terminates the cycle in time to prevent material from being dispersed over the machinery, he may not terminate the stuffing cycle upon completion of a fully stuffed link which thereby will result in a partially stuffed final link. This partially stuffed link can either be discarded, thereby wasting the material, or by expending time the material can be extracted from the casing for reuse.
It is, therefore, an object of this invention to provide a sensing means for automatically detecting the trailing portion of a shirred tubing on a stuffing horn assembly of a stuffing apparatus which will activate means for terminating the flow of material through said horn prior to the shirred casing being expended.
Another object of this invention is to provide sensing and control means for use on a stuffing apparatus to maximize the efficient use of shirred casings to be used on said apparatus.
A further object of this invention is to provide sensing means for automatically terminating the stuffing operation of a stuffing apparatus when the shirred tubing remaining on the stuffing horn of said apparatus is insufficient to provide a desired length of stuffed product.
Still another object of this invention is to provide a method whereby the detecting of movement of the trailing portion of a shirred casing disposed on a stuffing horn will automatically result in terminating the flow of material through said horn thereby terminating said flow prior to an expenditure of the shirred casing.